Spinal Cord Stimulation to Inhibit Afferent Feedback During Exercise in Heart Failure

Forty Heart Failure (>18 yrs. of age) will be recruited. The study will include a total of 2 visits. All experiments will take place at the Mayo Clinic; at the outpatient radiology for MRI screening, the Charlton Clinical Research Unit (CRU) for surgical suite for spinal cord stimulation placement and the Saint Mary's Hospital Clinical Research Unit for clinical exercise laboratory for the exercise protocol and overnight stay.

Study visit 1 will include eligibility screening, consenting process, completion of a health questionnaire and performance of a peak oxygen consumption (VO2) test. Additionally, subjects will undergo a screening lumbar MRI to ensure that there are no anatomical anomalies in or around the epidural area consistent with standard clinical practice for epidural stimulator lead placement associated with chronic pain syndromes.

Study visit 2 will include an overnight stay in the Saint Mary's Hospital Clinical Research Unit. Patients will check in to the CRU in the morning of day 1, visit 2. Prior to placement of stimulating electrodes an international normalized ratio (INR) will be checked to ensure safe clotting. An anesthesiologist will place the electrodes in the lumbar/thoracic epidural space in a manner that is standard for the clinical placement of temporary electrodes in humans. The participants will then transfer to the clinical exercise laboratory to start the exercise protocol. Participants will rest 15 minutes prior to starting exercise. Exercise will take place on a vertical bike where they will perform a submaximal cycling exercise at 30% of peak work for 29 minutes. Thigh cuffs will be placed on thigh bilaterally and inflated intermittently to pressures of 80m mmHg. After the testing is complete, participants will return to their room in the Clinical Research Unit for the rest of the day and sty over night.

On day two of visit two, participants will repeat the testing from day one with new randomization to determine reliability of testing performed on day one. After the exercise on day two of visit two, the spinal cord stimulator leads and radial arterial catheter will be removed.